Barca have sold Aubameyang to Chelsea in about 15 million deal,and gave Marcos Alonso as part of the deal.It is pretty fair because they wanted Aubameyang by all means since they are not getting the number of goals they required.He is brought to be a messiah to the club.So far,it's only Sterling that has been doing so much on the field,contributing and scoring goals as well.
Aubameyang helped them get to second on their league table which shows that his goal contribution has delivered good hope on the entire team.
Yes, I think this is a mutually beneficial transfer for both clubs. Chelsea clearly need a sharp attacking figure and Aubameyang is a suitable alternative according to Tuchel, besides at Barcelona there is also Lewandowski who of course is very difficult to replace if Aubameyang insists on staying. Marcos Alonso is also very much needed by Barcelona, he is a very experienced Spaniard. His arrival will add to their strength in the wing sector.